Valve for rock drills



July 22, 1952 P. H. NAST 2,604,073

VALVE FOR ROCK DRILLS Filed Feb. 25, 1948' 2 SHEETS-SHEET 1 PAUL H. NA ST INVENTOR. F I G. I

BY I

July 22, 1952 P. H. NAST 2,604,073

VALVE FOR ROCK DRILLS Filed Feb. 25. 1948 2 SHEETS-SHEET 2 Q 9' IZW\IZ FIG-.4-

PAU L H NAST INVENTOR.

Patented July 22, 1952 ets;

V ;:-.-f.: iI-Ai.vEFo1 ROCKITDBIYLLS c ,NastfWesfiiiaringfiield, Masstfassignor to'vvqrthingtp rum and Machinery Como g Y ration; Harrisomfl l, a corporation of Dela- 1r Application l tebruaryzi 1943 ,11s eha1m iaeigi'I i Thisfin vention. relates to rock "drills and nc-re particularly to a distributing valve for'controlling distribution of operatingpressure fluid t the,

actuated mechanism of a'percussive rock drill l Anlobj ect of r the present invention is to vprovide a distributing valve structure which will, insure. rapid'and positiveaction of the valve; and assure aheavy and forcei'ul blow of the percussive elementa gains t the working tool and one which is of ,simplified design and low costof manufacture.

The present invention comprehends a distributing valve structurejwherein 'the' valve is tripped by fluid pressurelacting on the valvearea,

s'ii'clif pressure fluidbeing ported from thejrock drill cylinder orlpiston chamber and controlled'by movement of the 'piston'and a valve distributing structure which embodies valve laps which cooperate with the valve to closeone port before the other is opened, thus eliminating any opposed action of pressure air on oppositesides of the piston even. for anfinstant and, consequently, reducing air consumption of the tooland increasing its'efii- 'More'specifically the invention embodies the combination of a valve stem on which a valve of charms. (c1. 121- 2s) 4 Figuree isfaper'spective view of thevalve supv in pressurefluid actuatedlrockj'drills, the piston 3' deliv 'ers' blows against 'the dri ll steel (not shown). or other tooloperated bythe rock'driill' proper;

' The cylinder 2 has an exhaust passage 4 open. ing out through an xhaustrvalve structured to the atrhosphere. The usual approved ,jty'pia of. v ratchet mechanism 8 is vmounted in ,the'r'ear end of th e housing: i u ervest 'jrotate the'tool" uniform. diameter 'reciprocateaQ said stem being provided with pressure supplypassages which opehijthrough annular lair grooves to supply air to thefcylinder and which air grooves are -ar1-1 ran'ged orjpositioned so that the valve laps are formedgwhen the valve box covenand valvehox are'ass'embled; thus eliminating intricate I andcostly machining ofeithertthe valve the valve box or the valve box cover and providing the valve structure which may be ground to exact dimensi'on's, as well as providing :perfect alignment of the parts so as to eliminate binding or crowding I oiflthe valve during operation.

' With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing a valve for rock drills of a preferred 'form embodying the invention, and the features forming the invention will be specifically pointed out in the claims.

' In the drawings; I Figure l is afragmentary longitudinal section through a rock drill showing the improved valve structure. I

Figure -Ii is ia fragmentary longitudinalsection through therockfdrill taken on a different'plane than that shown in Figure 1.

(not shownlj in theusual manner; Thefvalvej structure or assembly] is positioned between the ratchet mechanism 8 and the rearward'en'd 'o-f'the pistoncha'mber 2 and pressure fluid is delivered to the valve structure} from a suitable source of supplyof pressure'air (not shown) under con-f trol of an approved type of throttle valve 8 through the passage 9 in'the head I!) of the drill structure, and through the space H surrounding the ratchet mecha nism. r i

' The distributing valv 'structure comprises Id and-thevaIVe I-E. The valve jstem I4 is c'ylin dr'ic'a iirconstructiori andhas an annular flange it formed on its rearvvard -end,fwhich annular flange is providedfwith'an annular passage or" grooved? having'communication with the space ll so as to receive pressure'fiuid thereinto from the passage 9 anddeliver it to a plura'l'ity'jo'f longitudinally extending annularly or emu-m:- ferentially spaced passages l9 formed in the valve stem. The valve stem I4 is provided With'a pair of spaced annular air outlet grooves 26' and 2i. The spaced-annular groove 20 has communication with all of the longitudinally extendin air passages l9 and with' anannular .passage22 formed in the valve box cover. 'Ihe'housing lof the rock drill is provided with ports and passages 23 which establish communication between the 'annular passage 22 and-the pistonchambert at or near the'forward end of-the piston chamber; as shown; at 24; to supply pres'surefluid to the forward-end" of the piston chamber in advance ofthe-piston- 3 for returning the piston to its rearward-position in-the piston chamber 2.

The valve box I2 is provided with a plurality of passages 25 which communicate with the annular passage 2| and with the rear end of the piston chamber 2 for delivering pressure fluid behind the piston 3 for moving it on its forward blow imparting'stroke. I I I The'passage of the pressure fluid through the annular passage 22 and the passages 25 is controlled. by the distributing valve I which is mounted for limited reciprocatory movement upon the valve stem I4 and in a suitable space within the valve box I2 and valve box cover I3.

The valve I5 has an annular flange 26 formed thereon which extends into an annular recess 21 in the valve box 12. The annular recess 21 is wider or deeper than the width of the flange 26 so as to provide a space at either side of the flange 26, depending upon the position of the valve I5 and of the piston :3.

The housing I is provided with ports and passages indicated at 21' which open into the piston chamber 2 forwardly of the exhaust passage 4 and open into the annular recess 21 at-the forward end of this annular space so that as the piston returns on its rearward movement and uncovers the inlet of the passage 21' pressure air will be admittedfrom the piston chamber 2 into the annular recess '21 at the forward side of the flange 26'and move the valve I5 rearwardly to cut. off communication between the annular passage 22 with the piston chamber 2 through the passage 23 and open the annular inlet groove 2I to the passages 25 toadmit pressurefluid to the piston chamber behind the piston to move it on, its forward blow delivering stroke.

The housing 'I is also provided with a passage 28, which is ported to the piston chamber 2 rear-- \vardly of the exhaust passage 4 and is also ported to the annular space 21 at the rear side of the flange 26 so that as the piston moves forwardly and uncovers the port of communication between the passage 28 and the piston chamber 2 air will be admitted to the passage 28 and against the rearward side or face of the flange 26 for forcing the valve I5 forwardly to cut off communication between the annular pressure fluid inlet passage 2| and the passages 25 to cutoff flow of pressure fluid into the piston chamber 2 rearwardly of the piston.

In operation therefore, pressure fluid from a.

suitable source (not shown) is delivered by manually opening the throttle valve 8 to allow the pressure to pass through the passage 9 through the space II surrounding the ratchet mechanism 6 into the annular passage or groove I1 communicating with the said space H. I I I The pressure fluid expands into the longitudinal. passages I9 passing into the annular air outlet grooves 20. and 2I, where depending on the position of thevalve I5 will pass to either one or the other of the annular recesses 22 or 34, and accordingly the drill structure or housing I may be tilted substantially vertically upwardly or downwardly to force the valve by action of gravity so it will abut either the valve box cover I3 or the portion 33. The piston member 3 will also fall rearwardly o-r forwardly accordingly.

In normal operation the valve I5 will abut the portion 33 and the piston will be forward in the cylinder 2, thus air will expand into the annularspace 22, the passage 23 communicating there'- with and discharge through; the outlet 24 to move the piston 3 rearwardly substantially as is indi-- cated in Figure l of the drawings... a

The portion of the cylinder rearwardly of the drive-n the valve S m H s ves the (mar function .of holding the valvestem 14, valve box piston member 3 is under atmospheric pressure and accordingly offers little resistance to the piston members rearward movement so that the inlet of the passage 21 is uncovered and receives pressure fluid therein which expands to the forward 1 area of, the annular recess 21. to move the valve I5 in :a rearward. direction iwhifch cuts off the pressure fluid entering the annular space 22 and allows the pressure fluid to enter the annular space 34 to pass through the passage 25 into the cylinder 2 rearwardly of the piston member 3. This will stop the rearward motion and start the piston onIi-ts forward stroke.

As the piston 'moves forwardly it uncovers the inlet to the passage 28 and pressure fluid therein will flow through passage 28 into the rearward "area of the annular recess 21 causing the valve I5 to move forwardly which cuts ofi the pressure fluid entering the annular space 34 and allows the pressure fluid to enter the annular passage 22 once again wherein the pressure fluid'will 'pass down passage 23 to the outlet 24 to move the" piston on its rearward stroker; I I

It can readily bef'seen that'the same action will occur if the valve abutsthe, valve box 'I'3 initially except that the action will commence by moving the piston member '3 forwardly first;

As clearly shown in Figure 1 of the dra'v'vi'ngs; the valve box I2, valve box cov er' I3 and the annular flange IE on the val'vejstem l4 are all of uniform external'diameter and fit snugly within, the valve structure receiving bore formed in'the' housingv I. The valve'box I2ha's its portion,33

cover I3 and valve box 'I 2 all in tightly fitting asjsembled position as well'as an abutment forward end of the valve I5.

The annular pressure air inlet grooves and,

" 2| and the annular inlet passagelli ind he annular portion 34 of the passages 25are all constructed and arranged so that when'the valve box I2, valve box cover I3 and valve. stem I4 are in assembled positions, laps, indicated at 35 and 36'will be provided at the ends of the valve I5 so that during operation of the rock drill communie cation between onefof the pressure ai'r annular inlet grooves 20' 0132] with its'icorre'spondingan- 1 nularpassage 122 or 134 ..will be cutoff completely before communication is established between the other set and therebyopposed action'of pressure air against the pistonf3leven for anjinstant will be eliminated. I I I I Also by referencefto, Figure l offjthe drawings,

it will; be notedthat the valve I5 is of uniform external and internal. diameter throughout its, length except that its external diameter maybe said to be increased by the flange 2'6' andalso that the valve '15 is. free of any-undercuts, or ports or passages therein and thus expensive and delicate machining operations are eliminated the: construction of the valve, as ell as in the construction Qt thevalve stem, valve box. and

- I valve box cover and; these parts..may be accuratel-y ground. Furthermore, the construction of the valve'of the distributing valve structure or rather of its component parts is such that perfect alignment of all o f the -parts may be had and extremely close fits provided. Any mi saI-ign ment of the valve stem would tend to bin d -or crowd the valve, preventing. itfrom havingfree action. The valve stem. is supportedat the rear y t e-flange, t5 and at the. front by the portion 33 of thevalve box I2. .The simplified construc tion of the component parts iofjt-he'distributing fo he valve structure which permits grinding of these component parts and eliminates costly and intricate machining of laps, undercuts or the like, such as is usually found in valves of this type, as well as elimination of dowels to hold the parts together provides a simplified efiicient design of relatively low manufacturing cost.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified within the'invention defined by the claims.

What i claimed is:

1. In a percussive tool, a housing having a piston chamber therein, a reciprocatable piston in said chamber, an exhaust port for said chamber, and a distributing valve structure including a valve box with a valve stem therein, said valve box having a first air inlet passage formed therein communicating with the rear end of the piston chamber, a second air inlet passage formed in said valve box and said housing communicating with the forward end of said piston chamber, said valve stem having an annular groove in the upper end for communication with a source of pressure air supply, a plurality of longitudinally extending circumferentially spaced passages in said valve stem communicating with said annular groove for receiving pressure air therein, an upper and a lower annular air outlet passage formed on the outer circumference of said valve stem to provide lateral communication between said circumferentially spaced passages and said air inlet passages, a valve slidably mounted about said valve stem having a constant inner diameter substantially equal to the outer circumference of said valve stem, a flange on the outer circumference of said valve, a front and rear supply passage disposed on opposite sides of said housing providing communication between said piston chamber and opposed surfaces of said flange to allow air under pressure to move said valve whereby the flow of pressure air from said circumferentially spaced passages through said annular air outlet passages to reciprocate said piston will be controlled.

2. In a percussive tool as claimed in claim 1 wherein said valve stem and valve are supported in said valve box by an annular member having a driven fit over the end of said valve stem about its outer circumference adjacent and inwardly of said first air inlet passages in said valve box.

PAUL NAS'I.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,629,179 Slater .1 May 17, 1927 1,815,166 Smith July 21, 1931 1,965,264 Smith July 3, 1934 2,084,564 Smith June 22, 1937 2,162,036 Smith June 13, 1939 2,234,348 Mack Mar. 11, 1941 2,307,847 Morrison Jan. 12, 1943 

